First Division of Physical Therapy, School of Health Sciences, Sapporo Medical University, S1 W17 Chuo, Sapporo, Hokkaido, Japan; Department of Rehabilitation Medicine, Keio University School of Medicine, 35 Shinanomachi, Shjinjuku-ku, Tokyo, Japan; Department of Rehabilitation, Hokuto Hospital, Hokuto Social Medical Corporation, 7-5 Kisen, Inada-cho, Obihiro-shi, Hokkaido, Japan.
First Division of Physical Therapy, School of Health Sciences, Sapporo Medical University, S1 W17 Chuo, Sapporo, Hokkaido, Japan; Department of Rehabilitation Medicine, Keio University School of Medicine, 35 Shinanomachi, Shjinjuku-ku, Tokyo, Japan.
Neurosci Lett. 2021 Jan 10;741:135483. doi: 10.1016/j.neulet.2020.135483. Epub 2020 Nov 5.
Muscle spindles provide the greatest contribution to kinesthetic perception. Primary motor cortex (M1) excitability changes in parallel with the intensity of kinesthetic perception inputs from muscle spindles; M1 is therefore involved in kinesthetic perception. However, the causal relationship between changes in kinesthetic sensitivity and M1 excitability is unclear. The purpose of this study was to test whether artificially and sustainably modulated M1 excitability causes changes in kinesthetic sensitivity in healthy individuals. We evaluated motor evoked potentials (MEP) in Experiment 1 and joint motion detection thresholds (JMDT) in Experiment 2 before and after quadripulse transcranial magnetic stimulation (QPS). Nine healthy right-handed male volunteers were recruited. In each experiment, participants received QPS or sham stimulation (Sham) on separate days. MEP amplitude and JMDT were recorded before and at 0, 15, 30, 45, and 60 min after QPS and Sham. Our results showed that M1 excitability and kinesthetic sensitivity increased after QPS, whereas neither changed after Sham. In the five subjects who participated in both experiments, there was a significant moderate correlation between M1 excitability and kinesthetic sensitivity. Thus, the long-lasting change in kinesthetic sensitivity may be due to changes in M1 excitability. In addition, M1 may play a gain adjustment role in the neural pathways of muscle spindle input.
肌梭对动觉感知的贡献最大。初级运动皮层（M1）的兴奋性与肌梭传入的动觉感知强度平行变化；因此，M1 参与了动觉感知。然而，动觉敏感性变化和 M1 兴奋性之间的因果关系尚不清楚。本研究旨在测试人为且持续调节 M1 兴奋性是否会导致健康个体动觉敏感性的变化。我们在实验 1 中评估了运动诱发电位（MEP），在实验 2 中评估了关节运动检测阈值（JMDT），在四脉冲经颅磁刺激（QPS）前后。招募了 9 名健康的右利手男性志愿者。在每个实验中，参与者在不同的日子接受 QPS 或假刺激（Sham）。在 QPS 和 Sham 之前以及之后的 0、15、30、45 和 60 分钟记录 MEP 幅度和 JMDT。我们的结果表明，M1 兴奋性和动觉敏感性在 QPS 后增加，而 Sham 后则没有变化。在参加了两个实验的五名受试者中，M1 兴奋性和动觉敏感性之间存在显著的中度相关性。因此，动觉敏感性的持久变化可能归因于 M1 兴奋性的变化。此外，M1 可能在肌梭输入的神经通路中发挥增益调节作用。
